09/04/2012

"If Not Genetics, Then What?"

By David A. Kindig, MD, PhD

“If Not Genetics, Then What?” is the title of Chapter 6 in
the important 1994 population health book Why
Are Some People Healthy and Others Not: The Determinants of Health of
Populations. Canadian population health geneticist Patricia Baird
contributed a chapter on “The Role of Genetics in Population Health,” which concludes
as follows: “There are some disorders where the inherited metabolic machinery
of the individual will not allow normal functioning in the usual range of
environments; the associated diseases will usually burden the earlier part of
the human life cycle. These provide a real and appropriate place for genetic
service programs to contribute to population health. The complexities of the
web of causation for most common afflictions in adult life are likely to limit
the contribution of DNA identification of at risk genotypes. The potential for
wasting resources and causing harm is real and serious.”

I was prompted to return to this seminal text several weeks
ago after a series of New York Times
articles on modern genomics that included a front page story on tailoring
treatment for leukemia to a business page report of approval
in Europe of a gene therapy for treating a rare enzyme deficiency. Genetic
studies on Alzheimer’s proteins in mice have also raised the hope for a similar
way to way to cure or slow the progression of this serious and increasingly
prevalent health issue. The growing availability to sequence complete
individual human genomes raises the potential of widespread “personalized
medicine,” with drugs or genes available for whatever defects any person might
have.

How is a population health advocate to think about the
possibility of such scientific advances to improve overall health and reduce
disparities? It is so tempting to be lured into the fascination and the hope of
such technological cures, but why do I have significant reservations? It
probably because of the ideas laid out by Geoffrey Rose in his classic article “Sick
Individuals and Sick Populations” in which he asserts that “a large number
of people at small risk may give rise to more cases of disease than the small
number who are at high risk.” While there may be important advances with life-saving
treatments for rare diseases such as mentioned above, many complex diseases
like diabetes and obesity may have their genetic defects spread over many
locations rendering therapy complex and less likely, and many are the result of
complex gene-environment interactions. The best thinking such as from CDC
Public Health Genomics expert Muin Khoury, who argued for expanded evidence-based
strategies in a 2008 Health Affairs article: “the current low threshold allows
unsubstantiated technologies to enter into practice with the potential to
overwhelm the health system…while an excessively high threshold for evidence
could slow the integration of genomics into practice…also, variable coverage
and reimbursement policies can lead to differential access to technology,
exacerbating health disparities.”

Baird’s
warning about wasting resources and causing harm needs to be taken seriously. As
Don Berwick says, “waste is theft.” It is not anti-scientific to worry that
our American belief in technology and venture capitalism could result in much
waste, while less expensive investments we already know to be effective are
ignored. The problem is that it is hard
to predict the future, and decades from now there will certainly be important benefits
from genomic research, including both treatments and preventive interventions. We can only insist that the most careful
evidence on population health cost-effectiveness be used to guide investments,
rather than the potential for profit from very expensive therapies that benefit
few.

David A. Kindig, MD, PhD is Emeritus Professor of Population Health Sciences and Emeritus Vice-Chancellor for Health Sciences at the University of Wisconsin School of Medicine and Public Health. Follow him on twitter: @DAKindig.